With rapid development of communications technologies, various inter-RAT networks emerge as the times require, such as a Global System for Mobile Communications (GSM) network, a Wideband Code Division Multiple Access (WCDMA) network, and a Long Term Evolution (LTE) network. The plurality of inter-RAT networks correspond to a plurality of inter-RAT cells. As the plurality of inter-RAT cells have wide coverage, in a movement process of a terminal that accesses a cell, it is very possible that the terminal moves from a cell of one RAT (radio access technology) to a cell of another RAT, for example, from a cell of a WCDMA network to a cell of an LTE network. Therefore, to ensure that the terminal can always keep an access state in the movement process, the terminal needs to hand over between the inter-RAT cells.
Currently, a network architecture includes a plurality of types of core networks, and each type of core network can support a cell of only one RAT. For example, an LTE core network can support a cell of only an LTE network. Therefore, if a terminal is handed over between two inter-RAT cells, core networks of the two inter-RAT cells need to be crossed. A specific implementation process thereof includes: If the terminal moves from a source cell to a target cell, a source core network sends a handover request message to a target core network, and the target core network prepares a resource for the terminal after receiving the handover request message. Then, the target core network sends a handover response message to the source core network. The handover response message is used to indicate the resource already prepared by the target core network, and the handover response message carries configuration information corresponding to the resource. After receiving the handover response message, the source core network sends a handover command to the terminal by using a source base station. The handover command carries the configuration information. After receiving the handover command, the terminal is handed over to the target cell based on the configuration information, thereby implementing handover between the inter-RAT cells.
In the foregoing implementation process, the inventor finds that the prior art has at least the following problem: If a terminal is handed over between two inter-RAT cells, core networks need to be crossed in a handover process, and a large amount of signaling exchange exists between a source core network and a target core network, leading to a relatively large handover delay.